So you've got an iPhone XS in Space Grey. Congrats, so do 20 million other people. Maybe you have different cases but otherwise the hardware in all these phones are virtually identical. Yet you can tell with a glance that this is your phone. You can personalize apps and other elements of the home screen. It's your calendar and email and music.
What? You've dropped your phone over Niagara falls. Luckily you've backed up your data. So you go back to Apple and buy another Space Grey iPhone XS and restore your data. Physically it's a completely different phone but for all practical purposes it's though you still had the original phone. Your phone is not defined by the device but the data that resides on it.
It's not just phones. I can log into Google on anyone's Chrome browser and it will feel like my machine.
Now we've all heard about a future world where nobody owns cars and we get driven around in self-driving Ubers, Lyfts and Waymos. One argument against this world is that people feel connected to their cars and unwilling to commute in some generic vehicle. But one can also imagine the car knows who you are, knows how you like your music, your lighting, how you adjust your seats even how your car drives. It becomes your car. Maybe even has electronic bumper stickers that change to support your political party.
You can imagine the same for hotel rooms, your office, maybe even your apartment. It won't replicate your dog (or will it?) but as we get define more by our data than our things, do our things matter at all?